The present application relates to an interface comprising: an encoder including a stationary unit, a rotary unit which is rotatably coupled to the stationary unit, and a signal generation unit which is connected to a first circuit board and generates an electrical signal when the rotary unit is rotated; an actuator including a shaft which is fixed to the rotary unit, a handle which is fixed to the shaft and to which a force required for rotation of the shaft is input, an accommodation space which is provided in the handle to have a larger cross-sectional area than the cross-sectional area of the shaft, and a handle through-hole which passes through one surface of the handle so as to allow the accommodation space to communicate with the outside; and a display unit including a fastening body which passes through the shaft and is fixed to the stationary unit, an accommodation body which is fastened to the fastening body and is positioned in the accommodation space, and a display which is fixed onto a side of the accommodation body, facing the handle through-hole, and on which information is displayed.